Anti-shoplifting device



United States Patent 3,444,547 ANTI-SHOPLIFTING DEVICE 'Casimer 'Surek, Round Lake, 11]., assignor to Gefco Manufacturing Corp., Grays Lake, 11]., a corporation of Delaware Filed Oct. 8, 1965, Ser. No. 494,074 Int. Cl. G08b 21/00 US. Cl. 340-280 4 Claims ABSTRACT OF THE DISCLOSURE A tamper-proof anti-shoplifting device energizes an alarm circuit through the operation of a relay, in response to disconnection of an elongated, shielded, low impedance conductor. A second relay is connected for actuation when the first relay is deactuated, and also when the elongated conductor is short-circuited with respect to its shield to continuously energize the alarm until the apparatus is reset.

This invention relates to anti-shoplifting apparatus and more particularly to such apparatus in which an alarm signal is set off when an electrical circuit connection is broken.

In the prior art, anti-shoplifting devices have been designed to initiate an alarm in response to opening an electric circuit when an article being protected by such a device is removed from its position. Such prior devices have suffered, however, from several disadantages. For one thing, it has been possible for a shoplifter to terminate the alarm by quickly reconnecting the circuit, so that an attempted theft may not be detected. In addition, a theft may be signaled by only a short alarm. For example, one such prior art anti-shoplifting device comprises a buzzer with a battery source of power and a relay. The circuit components are interconnected with a conductor which is intertwined with the articles to be protected in such a way that such articles may not be removed without opening the electrical circuit formed by the conductor. In this type of device, however, it has been possible to disconnect the conductor long enough to separate it from a protected article, and then rapidly reconnect it in order to terminate the alarm signal produced by the buzzer. The alarm does not last long enough to provide an adequate signal.

Accordingly, it is the principal object of the present invention to provide anti-shoplifting apparatus of the type including a conductor intertwined with the articles to be protected, with provision for the continuance of an alarm signal after the conductor has been disconnected, irrespective of its reconnection.

Another disadvantage of prior art devices is that a self-contained power supply is required to guard against defeating its operation by merely disconnecting an external source of power. As a result, such devices normally contain batteries, and the constant current drain on the batteries makes frequent battery servicing and maintenance essential.

Accordingly, a further object of the present invention is to provide such apparatus including a power supply which may be energized from either an A.C., or a DC. source, thus eliminating the need to rely wholly on a self-contained source of power. In the present invention, interruption of the A.C. source automatically switches in a battery as an auxiliary power supply, so that interrupting the A.C. source does not disable the alarm device. Since there is no constant drain on the battery, servicing may be much less frequent.

A further disadvantage of prior art devices is that it has been possible to short circuit the conductor around an article with a short-circuiting wire or jumper. After the short-circuiting wire has been installed, no alarm is given when the conductor is disconnected and the protected articles are removed.

Accordingly, it is another object of the present invention to provide anti-shoplifting apparatus in which any attempt to install a short-circuiting wire will energize the alarm.

These and other objects and advantages of the present invention will be made manifest by an examination of this description and the accompanying drawings, in :which:

FIG. 1 is a prospective view of a system embodying the invention; and

FIG. 2 is a schematic circuit diagram of one embodiment of the present invention.

Referring now to FIG. 1, the use of the invention is illustrated. A housing 10 encloses the circuitry illustrated in FIG. 2, and is provided with a lock switch 12 by which the apparatus may be turned on and off, and a pilot lamp 19 which is adapted to be lighted to show when the apparatus is on. The housing is providde with a cover 14, having a front panel 11, an upper panel 13 and a corresponding lower panel, integrally connected together and adapted to slide forwardly out of interlocking engagement with the back panel and two side panles 15 of the housing 10, upon removing screws 17. A switch 58 (FIG. 2) is provided interiorly of the housing 10, and is adapted to be opened when the cover 14 is removed from the housing 10, functioning as an interlock. As described hereinafter, this will trigger the alarm unless the key switch 12 has been opened. The housing 10 is provided with a line cord 16, terminating in a plug 18, by which A.C. power is supplied to the circuitry of FIG. 2 within the housing 10.

A cable 20, comprising a closed loop having both of its ends emanating from the housing 10 is utilized in the manner illustrated, by intertwining the cable 20 with the articles to be protected, such as the coffee pot 21 illustrated in FIG. 1, so that the articles may not be removed from association with the conductor 20 without discon necting connectors 22. As will be more fully described hereinafter, the disconnection of the connectors 22 causes the initiation of an alarm signal which continues even though the connector 22 may be reconnected.

Referring to FIG. 2, one embodiment of the present invention is illustrated in which line cord 16 is connected to the primary of a transformer 24 through an A.C.-DC. switch 26. The secondary of the transformer 24 is provided with a center tap 28, and the voltage appearing at the secondary terminals is rectified in a full wave rectifier 31, including diodes 30 and 32. The DC voltage produced by the full wave rectifier is applied across the coil 34 of a relay 33, such that its armature 35 is normally closed with a contact 36, as illustrated in FIG. 2, applying the positive potential from the rectifier 31 to the line 38 and thence through the lock switch 12 to the line 42.

A battery 44 is provided, with its negative terminal connected to the center tap 28 of the transformer 24 and its positive terminal connected to the normally open contact 37 of the relay 33. If the A.C. power is interrupted, as for example by opening the switch 26, the relay coil 34 is de-energized and the contact 36 opens, interrupting the current path from the rectifier 31 to the line 38, and the armature 35 closes with the contact 37, completing the current path from the positive terminal of the battery 44 to the line 38. Hence, line 38 is always provided with a positive potential, irrespective of whether A.C. power is being furnished to the transformer 24, and the center tap 28 of the battery is similarly provided with a negative potential.

The cable 20 illustrated in FIG. 1 comprises a shielded cable having an inner conductor 43 and a coaxial outer conductor 45. The inner conductor 43 of the cable 20 has one end connected through the coil 50 of a relay 52 and through the cover-interlock switch 58 to the line 42 which is supplied with positive potential. The relay 52'has an armature 51 and a normally closed contact 53. The other end of the inner conductor 43 of the cable 20 is connected by a line 60 through a connector 62 and a cable 68 to one terminal of a low resistance sensing device 70. The other terminal of the device 70 is connected through the cable 68 and connector 62, and through a line 54 to the center tap 28. Thus, as long as the conductor 20 maintains a complete circuit between the negative potential present on line 54, through the coil 50 of the relay 52 to the positive potential on line 42, the coil 50 remains energized and the armature 51 remains out of contact with the contact 53. The lamp 19 is connected in parallel with the coil 50 and the cable 20, to indicate when they are energized.

A buzzer 64 is connected between the line 42 and the contact 53 of the relay 52, by a line 66, and is energized when the relay 52 is de-energized, thereby completing a circuit from the line 54 through the contact 53 to the buzzer 64.

The connector 62 is provided With four terminals which are adapted to be connected by the cable 68 to a monitor at a remote location. The low resistance sensing device 70, may conveniently be an ammeter or the like, and a current flowing through the device 70 indicates that the cable 20 has not been disconnected. Two other terminals of the connector 62 are connected across the terminals of the buzzer 64, by lines 73 and 75, and may be connected by the cable 68 to an alarm device at the remote location such as a buzzer or a lamp. A double check on the operation of the anti-shoplifting apparatus is available, because the current between the terminals 1 and 4 is interrupted, and a voltage appears between the terminals 2 and 3, when the cable 20 is disconnected. Either one of these eventualities indicates that one of the protected articles has been moved and the cable 20 has been disconnected.

The coil 72 of a relay 74 is connected in parallel with the buzzer 64, such that its armature 76 closes with its normally open contact 78 whenever the buzzer 64 is energized. The closing of the contact 78 with the armature 76 short circuits the corresponding contacts of relay 52, to hold in, or maintain the coil 72 of the relay 74 energized, irrespective of the condition of the relay 52. Thus, after disconnection of the cable 20, even if the cable is reconnected and the relay 52 is re-energized, the buzzer 64 remains energized through the contacts of the relay 74.

The outer conductor 45 of the cable 20 is connected by a lead 80 to the normally open contact 53 of the relay 52. The line 80 normally carries no current, but if an attempt is made to install a jumper wire around a protected article, a short circuit is formed between the central conductor 43 of the cable 20, and its outer conductor 45, which allows current to fiow through the buzzer 64, the line 80 and the outer conductor 45 to the short circuit, and thence through the inner conductor 43 andline 54 to the center tap 28. The coil 72 of the relay 74 is energized with the buzzer 64 and keeps the buzzer 64 energized even though the relay 52 may remain energized, the circuit formed by the inner conductor 43 of the cable 20 not necessarily having been interrupted. Thus, the apparatus of the present invention generates an alarm signal if any attempt to install a jumper is made.

Once the buzzer 64 has been energized, it can only be de-energized by opening the lock switch 12, which, when the cable 20 has been reconnected, resets the relay 74 by opening the circuit of its coil 72. Thus, there is no Way for a shoplifter to discontinue the alarm, once it has sounded. The cover interlock switch 58, being connected in series with the cable 20, produces the same effect as opening the circuit of the cable 20 when the housing 10 is tampered with.

What is claimed is:

1. In an anti-shoplifting device including signaling means, an elongated conductor, and first control means connected with the ends of said elongated conductor and adapted to energize said signaling means in response to a break in said conductor, the combination comprising an outer conductor surrounding said elongated conductor, and second control means connected with said elongated and outer conductors and adapted to energize said signaling means in response to a short circuit between said elongated and outer conductors said second control means comprising a voltage source, one terminal of said source being connected to one of said elongated and outer conductors, and a relay, said relay having a coil and a set of contacts, the opposite terminal of said source being connected to the other of said conductors through said relay coil so that said relay coil is in series with said voltage source and said short circuit, said set of contacts being connected in circuit with said signaling means and said voltage source.

2. Apparatus according to claim 1, wherein said set of contacts comprises normally open contacts interconnected directly between said elongated and outer conductors, so that short circuit conducts only until said relay is actuated.

3. Apparatus according to claim 2, wherein said signaling means is connected in parallel with said relay coil, one end of said parallel circuit being connected to one terminal of said voltage source, and the other end of said parallel circuit being connected to the opposite terminal of said source through said normally open contacts and said short circuit.

4. Apparatus according to claim 1, wherein said elongated conductor is the central conductor of a coaxial shielded cable and said outer conductor is the outer conductor of said cable.

References Cited UNITED STATES PATENTS 883,335 3/1908 OConnor 340-280 3,056,125 9/1962 Harry 340-274 1,747,194 2/1930 Thomas.

2,279,394 4/1942 Fountain 340 -276 2,814,795 11/1957 Spooner. 3,253,270 5/1966 Downer 340280 JOHN W. CALDWELL, Primary Examiner.

D. L. TRAFTON, Assistant Examiner.

US. Cl. X.R. 340256 

